^i8 



THEORETICAL BIOLOGY 



as strictly in conformity with plan as they do with the pro- 

 perties of the germ whose shaping they control. Beyond 

 that, the state of our knowledge at the present day does not 

 permit us to make any affirmation. 



It is only through a diagram that these mysterious re- 

 lations permit of concrete representation. Let us take as 

 the starting-point the impulse-system : through the individual 

 impulses i i i this affects the genes g g g in a super-mechanical 

 way (as is indicated by the dotted line). In a mechanical 

 way, which, however, in virtue of the impulse-invasion, is 

 striving towards a goal, the genes permit the reflex-arc to 

 arise, which fits into the indicator, on the one side by its re- 

 ceptor, and on the other by its effector. Since the nuclei of 

 the reserve plasm retain their genes, the influence of the 

 impulse-system on the body is kept persistent. Now we have 



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to assume that, at the critical point, the internal equilibrium 

 in the impulse-system veers round, for from this stage onwards 

 the directing of the construction of the developing body 

 becomes the directing of the working of the finished organism. 

 Once we have accustomed ourselves to the idea that the 

 whole direction of the organism, in the species and in the 

 community as well as in the individual, lies in the hands 

 of a super-mechanical natural power, which is to be recognised 

 not only through rules, but itself acts according to rules, all 



